1. Field of the Invention
This invention relates to a compression bonded semiconductor device assembly, and more particularly to improvements in a clamping apparatus for holding a semiconductor device between heat sinks or other support members.
2. Description of the Prior Art
Devices of the prior art have previously used clamping mechanisms for holding semiconductor devices in compression. Such mechanisms are adapted to put a semiconductor device having a predetermined number of PN junctions disposed therein in resilient and compressive contact with a heat sink or terminal conductor. The compressive force is supplied by a leaf spring, dish-shaped spring or the equivalent spring means which is held in compression by a pair of supporting plates disposed at opposite ends of the mechanism which in turn are attached to supporting rods disposed lengthwise along the mechanism. In such clamping mechanisms, the supporting plates are generally held in compression by an adjustment of a nut fitted onto a threaded portion disposed on one end of each supporting rod.
FIG. 1 shows by way of example such a clamping mechanism of the conventional construction wherein a solid supporting rod 1 passes through a supporting plate 2, a dish-shaped spring 3, a plate 4 for retaining the dish-shaped spring 3 and a nut 5. The mechanism of FIG. 2 is similar to that of FIG. 1 except that a combined leaf spring and supporting plate 6 performs the dual function of the springs 3 and plate 2 of FIG. 1.
In the mechanism of FIG. 1, a compressive contacting force for a semiconductor device and a heat sink or the like is given by the dish-shaped springs 3 and held by the nut 5 through the retaining plate 4.
In the mechanism of FIG. 2, the compressive contacting force is held by the combined leaf spring and supporting plate 6 which is held in place by the nut 5.
To assemble the mechanism of either of FIGS. 1 and 2, a system may be adopted, for example, using a jig externally applied to the retaining plate 2 or the supporting plate 6, then applying a prescribed force to a semiconductor device by means of the jig and a press, then fastening the nut 5 when the spring 3 or 6 is compressed nearly flat and finally removing the external force.
Such conventional clamping mechanisms are inefficient, slow and have the disadvantage of causing variations in compressive force due to human error in fastening the nuts. Furthermore, the operation is difficult to automate.
Accordingly, it is an object of the present invention to provide an efficient mechanism for clamping semiconductor devices which is suitable for automatic assembly, thus eliminating the above-mentioned problems of prior art mechanisms.